In the art of making shingles, it is known to make multi-tab shingles, with the tabs in a tab area at a lower end of a shingle and having a headlap area above the tab area. The individual tabs are separated by slots cut into the tab area from a lower edge of the shingle. It is also known that shingles can be constructed to be of the multi-tab type, comprising, three, four, or five or more tabs per shingle.
It is also known in the shingle art that it is desirable to make shingles that give the appearance, when installed on a roof, of natural materials, such as wooden cedar shakes, slate, etc. To this end, sometimes the lower edges of the tabs are irregularly shaped, and in some cases the tabs may have variations in vertical length, so that the lower edges of the tabs are not always necessarily in line.
In the manufacture of shingles, it is further known to manufacture shingles from what is originally an endless or substantially endless sheet of shingle material, generally comprising a mat which may be constructed of either organic or inorganic material, and often of a fiberglass material, with the mat then being impregnated and coated with asphalt or other bituminous material, to which granules are applied. Such a layer of shingle material is then cut to form individual shingles of a desired length and width. One way of cutting the shingle material into individual shingles, is to run the shingle material between one or more pairs of cutting rollers. For example, if single layer shingles are manufactured, the pair of cutting rollers may comprise a cutting roll and a back-up or anvil roll, whereby, as the shingle material is conveyed therebetween, cutting blades carried on the cutting roller press through the shingle material, pressing the same against a die roller, such that longitudinal cuts, including spaced apart tab-forming slots are cut into the shingle material and lower edges of the tabs and the upper edge of the headlap area are likewise cut.
Generally, the same cutting roll that is described above is also furnished with one or more cutting blades that will make the transverse cuts necessary to sever the shingle material transversely to preselected lengths, after which the individual shingles may then be stacked for shipment.
In the manufacture of multi-layer (also called laminated) shingles the first pair of cutting rolls may lack the cutting blades that are responsible for severing the shingle material transversely to preselected lengths. Rather, the cutting blades on the first cutting roll may be used as a "pattern cutter", cutting a repeating pattern in an endless, or substantially endless manner. Other layer(s) comprising the multi-layer shingle would generally also be cut by the first cutting roll. Following this cutting action the layers comprising the multi-layer shingle would generally be positioned underneath one another, and laminated to one another with generally asphalt based adhesive. Generally, thereafter, the laminated layers may be severed into preselected shingle lengths in any suitable manner, such as by running the shingle material between another pair of rolls which are furnished with one or more cutting blades that make the transverse cuts necessary to sever the shingle material transversely to preselected lengths, after which the individual shingles may then be stacked for shipment.